Pub Date : 2025-01-01DOI: 10.1590/1517-7076-rmat-2025-0268
Lina Wang, Lili Li, Zhongzheng Pang, Xuesong Hui
Abstract This study reports a facile synthesis of Au-modified Nano-SnS2 composites through a combined water-thermal and in situ chemical reduction method, aimed at advancing low-temperature gas sensing technology. Comprehensive structural analyses using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy confirmed that incorporation of Au nanoparticles significantly alters the nanostructure. The results reveal that optimal Au loading at 0.5 wt% refines the crystallite size from approximately 25 nm to 20–23 nm, while uniformly distributed Au particles with diameters of 3–5 nm effectively form Schottky junctions that enhance interfacial charge transfer. Gas sensing measurements demonstrate that the sensor response increases from 4.7 at 1 ppm to 22.6 at 10 ppm NO2, and a linear correlation (R2 = 0.998) was observed in the lower concentration range of 1–4 ppm. Furthermore, the optimal operating temperature decreased from 140°C for the unmodified sensor to 120°C, contributing to reduced power consumption. The transient response characteristics also improved markedly, with a response time of 42 s and a recovery time of 127 s, in contrast to 220 s and 520 s for the pristine material. Long-term stability tests over 40 days revealed less than 4% variation in sensor performance, and selectivity experiments confirmed a strong preference for NO2 over other interfering gases. Overall, the synergistic effects of Au-induced electronic sensitization and catalytic activity result in enhanced sensitivity, faster kinetics, and excellent durability. These significant findings offer valuable insights for designing highly efficient sensors for environmental monitoring, paving the way for future sensor technology.
{"title":"Novel Au-modified Nano-SnS2: synthesis, structural analysis, and enhanced gas sensing properties","authors":"Lina Wang, Lili Li, Zhongzheng Pang, Xuesong Hui","doi":"10.1590/1517-7076-rmat-2025-0268","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2025-0268","url":null,"abstract":"Abstract This study reports a facile synthesis of Au-modified Nano-SnS2 composites through a combined water-thermal and in situ chemical reduction method, aimed at advancing low-temperature gas sensing technology. Comprehensive structural analyses using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy confirmed that incorporation of Au nanoparticles significantly alters the nanostructure. The results reveal that optimal Au loading at 0.5 wt% refines the crystallite size from approximately 25 nm to 20–23 nm, while uniformly distributed Au particles with diameters of 3–5 nm effectively form Schottky junctions that enhance interfacial charge transfer. Gas sensing measurements demonstrate that the sensor response increases from 4.7 at 1 ppm to 22.6 at 10 ppm NO2, and a linear correlation (R2 = 0.998) was observed in the lower concentration range of 1–4 ppm. Furthermore, the optimal operating temperature decreased from 140°C for the unmodified sensor to 120°C, contributing to reduced power consumption. The transient response characteristics also improved markedly, with a response time of 42 s and a recovery time of 127 s, in contrast to 220 s and 520 s for the pristine material. Long-term stability tests over 40 days revealed less than 4% variation in sensor performance, and selectivity experiments confirmed a strong preference for NO2 over other interfering gases. Overall, the synergistic effects of Au-induced electronic sensitization and catalytic activity result in enhanced sensitivity, faster kinetics, and excellent durability. These significant findings offer valuable insights for designing highly efficient sensors for environmental monitoring, paving the way for future sensor technology.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.scielo.br/j/rmat/a/9T3B47VbSSzvCSHYBsKfxDP/?lang=en&format=pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147331069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1590/1517-7076-rmat-2025-0416
Shupei Li, Shuangchun Yang, Xinyue Zhang, Feng Qi, Mingze Guo, Yi Pan
ABSTRACT Chemically modified bentonite has greatly improved its performance due to its structural adjustability. In this study, the modification of bentonite was accomplished through the method of sodium intercalation adsorption. The temperature-sensitive modified bentonite was prepared by initially sodifying bentonite with sodium carbonate and sodium pyrophosphate, intercalating CMC into the interlayer structure of sodified bentonite, and adsorbing N-isopropyl acrylamide (NIPAM) on the surface of bentonite. Further, the deep-water bentonite drilling fluid system was prepared. The optimal sodification conditions were determined by the single-factor control variable method of expansion volume as a drug-bentonite ratio of sodium carbonate of 1:9 and an addition amount of sodium pyrophosphate of 0.5%. The ratio of sodified bentonite to CMC drug-bentonite is 30:1. The addition amount of NIPAM was determined to be 0.5 g through the orthogonal experiment method of two factors of temperature and viscosity. Meanwhile, the temperature-sensitive modification mechanism and performance changes were analyzed through microscopic characterization and performance testing. The results show that the modified bentonite can play a significant temperature regulation role within the temperature range of 60°C and above, and the prepared drilling fluid system has good rheological properties under the condition of temperature change.
{"title":"Preparation of temperature-sensitive CMC-BENTONITE-NIPAM applied to deepwater drilling fluids","authors":"Shupei Li, Shuangchun Yang, Xinyue Zhang, Feng Qi, Mingze Guo, Yi Pan","doi":"10.1590/1517-7076-rmat-2025-0416","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2025-0416","url":null,"abstract":"ABSTRACT Chemically modified bentonite has greatly improved its performance due to its structural adjustability. In this study, the modification of bentonite was accomplished through the method of sodium intercalation adsorption. The temperature-sensitive modified bentonite was prepared by initially sodifying bentonite with sodium carbonate and sodium pyrophosphate, intercalating CMC into the interlayer structure of sodified bentonite, and adsorbing N-isopropyl acrylamide (NIPAM) on the surface of bentonite. Further, the deep-water bentonite drilling fluid system was prepared. The optimal sodification conditions were determined by the single-factor control variable method of expansion volume as a drug-bentonite ratio of sodium carbonate of 1:9 and an addition amount of sodium pyrophosphate of 0.5%. The ratio of sodified bentonite to CMC drug-bentonite is 30:1. The addition amount of NIPAM was determined to be 0.5 g through the orthogonal experiment method of two factors of temperature and viscosity. Meanwhile, the temperature-sensitive modification mechanism and performance changes were analyzed through microscopic characterization and performance testing. The results show that the modified bentonite can play a significant temperature regulation role within the temperature range of 60°C and above, and the prepared drilling fluid system has good rheological properties under the condition of temperature change.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147333476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-08DOI: 10.1590/1517-7076-rmat-2023-0151
Zhenlong Mo
Graphene oxide (GO) has attracted more and more attention in asphalt pavement due to its excellent performance. However, most current research is limited to GO modified base asphalt, and the modification effect is insignificant. In this paper, GO / SBS-modified asphalt was prepared by high-speed shearing. The effects of GO on the physical properties, storage stability, low-temperature performance, and aging resistance of SBS-modified asphalt were studied. A low-temperature beam bending test analyzed the low-temperature performance of GO / SBS composite modified asphalt mixture before and after aging. The results show that adding GO improves SBS-modified asphalt’s high-temperature performance, aging resistance, and storage stability. When the con - tent of GO is 0.75%, the physical properties of modified asphalt are the best. The low-temperature rheological properties of modified asphalt with GO before aging are slightly lower than those of SBS-modified asphalt. However, adding GO improves the low-temperature rheological properties of GO/SBS modified asphalt after aging. GO-modified asphalt slightly improves the low-temperature toughness of the mixture under non-aging and short-term aging. However, it still makes the mixture maintain good low-temperature performance under long-term aging. GO / SBS modified asphalt mixture has excellent low-temperature crack resistance before and after aging, and GO / SBS composite modified asphalt can effectively alleviate the damaging effect of aging on the low-temperature crack resistance of asphalt mixture and prolong the service life of the pavement.
{"title":"Study on the performance and aging low temperature performance of GO / SBS modified asphalt","authors":"Zhenlong Mo","doi":"10.1590/1517-7076-rmat-2023-0151","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0151","url":null,"abstract":"Graphene oxide (GO) has attracted more and more attention in asphalt pavement due to its excellent performance. However, most current research is limited to GO modified base asphalt, and the modification effect is insignificant. In this paper, GO / SBS-modified asphalt was prepared by high-speed shearing. The effects of GO on the physical properties, storage stability, low-temperature performance, and aging resistance of SBS-modified asphalt were studied. A low-temperature beam bending test analyzed the low-temperature performance of GO / SBS composite modified asphalt mixture before and after aging. The results show that adding GO improves SBS-modified asphalt’s high-temperature performance, aging resistance, and storage stability. When the con - tent of GO is 0.75%, the physical properties of modified asphalt are the best. The low-temperature rheological properties of modified asphalt with GO before aging are slightly lower than those of SBS-modified asphalt. However, adding GO improves the low-temperature rheological properties of GO/SBS modified asphalt after aging. GO-modified asphalt slightly improves the low-temperature toughness of the mixture under non-aging and short-term aging. However, it still makes the mixture maintain good low-temperature performance under long-term aging. GO / SBS modified asphalt mixture has excellent low-temperature crack resistance before and after aging, and GO / SBS composite modified asphalt can effectively alleviate the damaging effect of aging on the low-temperature crack resistance of asphalt mixture and prolong the service life of the pavement.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88142972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the feasibility of low-grade hard asphalt in high-temperature regions. We conducted an analysis of the high-temperature rheological properties of asphalt before and after short-term and long-term aging using the dynamic shear rheological (DSR) test and multi-stress creep recovery (MSCR) test. Additionally, the road performance of the asphalt mixture was studied by rutting test and low temperature beam bending test. The results indicate that the 30# asphalt demonstrates superior anti-rutting performance compared to the 50# asphalt. Furthermore, the rutting factor and fatigue factor of the 30# asphalt during aging are significantly higher than those of the 50# asphalt. With increasing temperature, stress level, and stress action time, the strain of the asphalt gradually increases. The unrecoverable creep compliance of the 50# asphalt exceeds that of the 30#. Although the high-temperature performance of the 30# asphalt mixture outperforms that of the 50# asphalt mixture, it exhibits lower flexural tensile strength and deformation ability at low temperatures compared to the 50# asphalt mixture. Overall, low-grade asphalt demonstrates relatively stable stress variations and exhibits good high-temperature stability.
{"title":"Rheological properties and engineering application of low-grade asphalt mixture","authors":"Lianguo Song, Pengcheng Tu, Xiao-lu Xie, Jingjing Fan, Lulu Hou, Jie Gao","doi":"10.1590/1517-7076-rmat-2023-0208","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0208","url":null,"abstract":"This study investigates the feasibility of low-grade hard asphalt in high-temperature regions. We conducted an analysis of the high-temperature rheological properties of asphalt before and after short-term and long-term aging using the dynamic shear rheological (DSR) test and multi-stress creep recovery (MSCR) test. Additionally, the road performance of the asphalt mixture was studied by rutting test and low temperature beam bending test. The results indicate that the 30# asphalt demonstrates superior anti-rutting performance compared to the 50# asphalt. Furthermore, the rutting factor and fatigue factor of the 30# asphalt during aging are significantly higher than those of the 50# asphalt. With increasing temperature, stress level, and stress action time, the strain of the asphalt gradually increases. The unrecoverable creep compliance of the 50# asphalt exceeds that of the 30#. Although the high-temperature performance of the 30# asphalt mixture outperforms that of the 50# asphalt mixture, it exhibits lower flexural tensile strength and deformation ability at low temperatures compared to the 50# asphalt mixture. Overall, low-grade asphalt demonstrates relatively stable stress variations and exhibits good high-temperature stability.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88021418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-04DOI: 10.1590/1517-7076-rmat-2023-0182
Ravisankar Venugopal, N. Muthusamy, Balasundaram Natarajan, Venkatesan Govindan
To meet the present needs of concrete consumption, it is the need of the hour to discover different alterna - tives and unique techniques. By Incorporating the latest trends, Polymer Concrete (PC) and Fibre-Reinforced Concrete (FRC) are being used to improve the strength of concrete. It is proposed to produce M30 grade Fibre Reinforced Polymer Concrete (FRPC) with the help of Polyester Resins (PR), Polypropylene Fibres (PF) and Recycled Waste Plastics (RWPA). FRPC is a combination of three different variables of different replacement percentages, which requires extensive and detailed experimentation to optimize each variable used in this investigation. In this study (research), optimization was done by keeping the two variables constant. To reduce the number of experiments, optimization of ingredients was done by statistical modelling technique of Central Composite Design (CCD). In conclusion, the optimal input parameters for achieving a 28-day CS are determined to be 12.05% PR, 2.19% PF, and 30% RWPA. These findings are based on the analysis of experimental results, statistical modelling, and the CCD approach, demonstrating the successful optimization and correlation between the input parameters and the desired CS output.
{"title":"Statistical optimization of fibre reinforced polymer concrete made with recycled plastic aggregates by central composite design","authors":"Ravisankar Venugopal, N. Muthusamy, Balasundaram Natarajan, Venkatesan Govindan","doi":"10.1590/1517-7076-rmat-2023-0182","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0182","url":null,"abstract":"To meet the present needs of concrete consumption, it is the need of the hour to discover different alterna - tives and unique techniques. By Incorporating the latest trends, Polymer Concrete (PC) and Fibre-Reinforced Concrete (FRC) are being used to improve the strength of concrete. It is proposed to produce M30 grade Fibre Reinforced Polymer Concrete (FRPC) with the help of Polyester Resins (PR), Polypropylene Fibres (PF) and Recycled Waste Plastics (RWPA). FRPC is a combination of three different variables of different replacement percentages, which requires extensive and detailed experimentation to optimize each variable used in this investigation. In this study (research), optimization was done by keeping the two variables constant. To reduce the number of experiments, optimization of ingredients was done by statistical modelling technique of Central Composite Design (CCD). In conclusion, the optimal input parameters for achieving a 28-day CS are determined to be 12.05% PR, 2.19% PF, and 30% RWPA. These findings are based on the analysis of experimental results, statistical modelling, and the CCD approach, demonstrating the successful optimization and correlation between the input parameters and the desired CS output.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73344692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-04DOI: 10.1590/1517-7076-rmat-2023-0176
Ala’eddin A. Saif, Yen Chin Teh, Prabakaran Poopalan
Ba 1-x Gd x TiO 3 thin films have been fabricated at different Gd 3+ ionic concentrations, film thicknesses, and anneal - ing temperatures using the sol-gel method. The refractive index of the Ba 1-x Gd x TiO 3 films on a silicon substrate is characterized using Spectroscopic Ellipsometry (SE), where the ellipsometry angles Ψ and Δ are fitted very well with the Cauchy dispersion model. The results show that the refractive index at 632.8 nm decreases from 2.18 to 1.892 with the increase of the Gd 3+ ratio, while it increases with film thickness and annealing tempera - ture. This trend for refractive index variation is explained based on interatomic spacing and density densification of the films. Using Wemple–Di Domenico (WDD) model shows that the dispersion energy increases with film thickness and annealing temperature and decreases with Gd 3+ doping. The relatively high refractive index of the samples supports the possibility of using Ba 1-x Gd x TiO 3 thin films as AR coating for solar cells.
{"title":"A study on the refractive index of sol-gel Ba1-xGdxTiO3 thin films using spectroscopic ellipsometry","authors":"Ala’eddin A. Saif, Yen Chin Teh, Prabakaran Poopalan","doi":"10.1590/1517-7076-rmat-2023-0176","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0176","url":null,"abstract":"Ba 1-x Gd x TiO 3 thin films have been fabricated at different Gd 3+ ionic concentrations, film thicknesses, and anneal - ing temperatures using the sol-gel method. The refractive index of the Ba 1-x Gd x TiO 3 films on a silicon substrate is characterized using Spectroscopic Ellipsometry (SE), where the ellipsometry angles Ψ and Δ are fitted very well with the Cauchy dispersion model. The results show that the refractive index at 632.8 nm decreases from 2.18 to 1.892 with the increase of the Gd 3+ ratio, while it increases with film thickness and annealing tempera - ture. This trend for refractive index variation is explained based on interatomic spacing and density densification of the films. Using Wemple–Di Domenico (WDD) model shows that the dispersion energy increases with film thickness and annealing temperature and decreases with Gd 3+ doping. The relatively high refractive index of the samples supports the possibility of using Ba 1-x Gd x TiO 3 thin films as AR coating for solar cells.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85483725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
River sand is becoming increasingly scarce. As a result, an alternative material is required to replace river sand in order to save river sand. In the construction of quality concrete, artificial aggregate is now frequently employed as a substitute for river sand. Coconut fibre ash (CFA) aggregate obtained from Coconut fibre is prev - alent in India. Partially replacing river sand (fine aggregate) with presaturated CFA aggregate for self curing purpose is presented in the paper. Fine aggregates were replaced by CFA aggregate by 5%, 10%, 15%, 20% and 25% by volume. The workability and strength characteristics of the concrete are studied. Internal curing is the solution to today's water scarcity's insufficient curing. During compared to other mixtures, test results show that the concrete mix with 20% CFA aggregate produced better results when self curing.
{"title":"Influence of presaturated coconut fibre ash pellets in concrete","authors":"Gopi Rajamanickam, Saravanakumar Ramasamy, Elango Krishnan Soundararajan, Kathiresan Karuppanan, Chandrasekar Arumugam","doi":"10.1590/1517-7076-rmat-2023-0190","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0190","url":null,"abstract":"River sand is becoming increasingly scarce. As a result, an alternative material is required to replace river sand in order to save river sand. In the construction of quality concrete, artificial aggregate is now frequently employed as a substitute for river sand. Coconut fibre ash (CFA) aggregate obtained from Coconut fibre is prev - alent in India. Partially replacing river sand (fine aggregate) with presaturated CFA aggregate for self curing purpose is presented in the paper. Fine aggregates were replaced by CFA aggregate by 5%, 10%, 15%, 20% and 25% by volume. The workability and strength characteristics of the concrete are studied. Internal curing is the solution to today's water scarcity's insufficient curing. During compared to other mixtures, test results show that the concrete mix with 20% CFA aggregate produced better results when self curing.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"23 2 PT. 1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82926453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-04DOI: 10.1590/1517-7076-rmat-2023-0214
Ce Sun, Xiaoqing Li, Fanghui Guo, Junru Li, Lianjun Cheng, P. Zhang
By performing tensile tests in the temperature range of 800°C to 1200°C, the thermoplastic behavior of microal-loyed and unmicroalloyed new martensitic low-density steels were investigated, and the mechanism of the effect of Nb and V microalloying on the thermoplasticity was revealed. The results showed that both microalloyed and unmicroalloyed steels have good thermoplasticity and the plasticity increased with increasing deformation temperature. The microalloyed steels above 1000°C could have their high-temperature plasticity significantly enhanced by Nb, V microalloying, while the microalloyed steels at or below 1000°C could have their plasticity reduced. When the deformation temperature exceeds 1000°C, complete recrystallization occurs in both microal-loyed and unmicroalloyed steels. The Nb, V microalloys were able to refine the recrystallized grains, which could obtain a stronger resistance to crack expansion and give the microalloyed steels better high-temperature plasticity. When the deformation temperature at or below 1000°C, the unmicroalloyed steel exhibited significant recrystallization. The presence of numerous small-sized NbC precipitation phases, abundant in the microal-loyed steel, hindered the recrystallization. This made dynamic recrystallization of microalloyed steels almost non-existent when deformation occurred at lower temperatures, which lead to lower plasticity compared to the unmicroalloyed steel.
{"title":"Effects of Nb and V microalloying on the thermoplasticity of new martensitic low-density steels","authors":"Ce Sun, Xiaoqing Li, Fanghui Guo, Junru Li, Lianjun Cheng, P. Zhang","doi":"10.1590/1517-7076-rmat-2023-0214","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0214","url":null,"abstract":"By performing tensile tests in the temperature range of 800°C to 1200°C, the thermoplastic behavior of microal-loyed and unmicroalloyed new martensitic low-density steels were investigated, and the mechanism of the effect of Nb and V microalloying on the thermoplasticity was revealed. The results showed that both microalloyed and unmicroalloyed steels have good thermoplasticity and the plasticity increased with increasing deformation temperature. The microalloyed steels above 1000°C could have their high-temperature plasticity significantly enhanced by Nb, V microalloying, while the microalloyed steels at or below 1000°C could have their plasticity reduced. When the deformation temperature exceeds 1000°C, complete recrystallization occurs in both microal-loyed and unmicroalloyed steels. The Nb, V microalloys were able to refine the recrystallized grains, which could obtain a stronger resistance to crack expansion and give the microalloyed steels better high-temperature plasticity. When the deformation temperature at or below 1000°C, the unmicroalloyed steel exhibited significant recrystallization. The presence of numerous small-sized NbC precipitation phases, abundant in the microal-loyed steel, hindered the recrystallization. This made dynamic recrystallization of microalloyed steels almost non-existent when deformation occurred at lower temperatures, which lead to lower plasticity compared to the unmicroalloyed steel.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"749 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76857040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1590/1517-7076-rmat-2023-0106
Augusto Prata Sigeiro, R. Marcomini
RESUMO No presente estudo, lotes de placas de zircônia estabilizada com 8% mol de ítrio (TZ8Y) foram fabricados pela técnica de colagem de fita, variando entre eles a composição da suspensão, como o volume de sólidos e os teores de ligantes, de plastificante do tipo I e de plastificante do tipo II com o intuito de verificar a influência destes parâmetros e do comportamento tixotrópico da suspensão sobre o empenamento do produto final. Após sinterizadas, a topografia das placas foi mapeada por meio de um relógio comparador, tomando medidas sobre a superficia das placas em um sistema de coordenadas, e, a partir desse sistema, foi definido um índice numérico que quantifica a planicidade das amostras. A influência foi investigada através de uma análise estatística bivariada, relacionando o índice de planicidade com cada um dos parâmetros alvo. A análise apresentou uma correlação negativa forte e significativa pelo teste de Spearman (⍴ ≅ 0,95 e valor-p < 10–3) entre o teor de plastificante do tipo I e a planicidade das placas produzidas, porém para os outros parâmetros analisados a correlação não pôde ser considerada estatisticamente significativa. Além disso, os resultados mostraram também que a utilização de um pós processamento nas fitas à verde, como uma laminação, melhorou substancialmente a planicidade das placas após a sinterização.
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Pub Date : 2023-09-01DOI: 10.1590/1517-7076-rmat-2023-0085
Thaís Ramos Capai Jardim, M. Câmara, F. C. Magalhães, Anderson Júnior dos Santos
RESUMO O atrito nas interfaces ferramenta/cavaco e ferramenta/peça é complexo dificultando a determinação do coeficiente de atrito nos processos de usinagem. Assim, vários ensaios tribológicos foram desenvolvidos para simular as condições de corte e determinar o coeficiente de atrito. Este trabalho apresentou análise comparativa do coeficiente de atrito entre o aço ABNT 1045 e WC-10Co revestido com AlCrN por meio de dois métodos: ensaio de torneamento e ensaio de compressão de anel à quente. O ensaio de torneamento foi realizado com corte oblíquo nas velocidades de corte 150 e 220 m/min. A aquisição dos sinais das componentes de força da usinagem por meio de um dinamômetro. O ensaio de compressão de anel foi realizado nas temperaturas de 200 e 400 °C. Os coeficientes de atrito foram obtidos por meio de modelos matemáticos. A análise estatística do coeficiente de atrito apontou equivalência do coeficiente de atrito no ensaio de torneamento na velocidade de corte 150 m/min com o ensaio de compressão de anel à quente 200 °C. Assim como no ensaio de torneamento na velocidade de corte 220 m/min com o ensaio de compressão de anel à quente 400 °C. A análise macrográfica do anel após a deformação no ensaio de compressão de anel observou a influência da temperatura de ensaio no deslocamento do raio neutro. A análise superficial dos anéis e das matrizes do ensaio de compressão foi realizada por meio de microscopia óptica (MO) e rugosidade Ra, onde observou-se o aumento da rugosidade após o ensaio e a presença de desgaste abrasivo.
{"title":"Avaliação da aplicabilidade do ensaio de compressão de anel à quente para determinar o coeficiente de atrito no ensaio de torneamento do aço ABNT 1045 por meio de análise estatística","authors":"Thaís Ramos Capai Jardim, M. Câmara, F. C. Magalhães, Anderson Júnior dos Santos","doi":"10.1590/1517-7076-rmat-2023-0085","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0085","url":null,"abstract":"RESUMO O atrito nas interfaces ferramenta/cavaco e ferramenta/peça é complexo dificultando a determinação do coeficiente de atrito nos processos de usinagem. Assim, vários ensaios tribológicos foram desenvolvidos para simular as condições de corte e determinar o coeficiente de atrito. Este trabalho apresentou análise comparativa do coeficiente de atrito entre o aço ABNT 1045 e WC-10Co revestido com AlCrN por meio de dois métodos: ensaio de torneamento e ensaio de compressão de anel à quente. O ensaio de torneamento foi realizado com corte oblíquo nas velocidades de corte 150 e 220 m/min. A aquisição dos sinais das componentes de força da usinagem por meio de um dinamômetro. O ensaio de compressão de anel foi realizado nas temperaturas de 200 e 400 °C. Os coeficientes de atrito foram obtidos por meio de modelos matemáticos. A análise estatística do coeficiente de atrito apontou equivalência do coeficiente de atrito no ensaio de torneamento na velocidade de corte 150 m/min com o ensaio de compressão de anel à quente 200 °C. Assim como no ensaio de torneamento na velocidade de corte 220 m/min com o ensaio de compressão de anel à quente 400 °C. A análise macrográfica do anel após a deformação no ensaio de compressão de anel observou a influência da temperatura de ensaio no deslocamento do raio neutro. A análise superficial dos anéis e das matrizes do ensaio de compressão foi realizada por meio de microscopia óptica (MO) e rugosidade Ra, onde observou-se o aumento da rugosidade após o ensaio e a presença de desgaste abrasivo.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90926038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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